Charles roland chambers



(No Model.)

T. V. HUGHES & CHAMBERS.

MANUFACTURE OF 0 N FILAMENTS.

No. 405,480. v I Patented June 18, 1889.

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74 2772 anew. ww Z 42 3} Tc- PATENT OFFICE.

THEOPHILUS VAUGHAN HUGHES, OF HOLYlVELL, NORTH W ALES, AND

CHARLES ROLAND CHAMBERS, MIDDLESEX, ENGLAND.

OF SOUTH KENSINGTON, COUNTY OF MANUFACTURE Ol- CARBON FILAMENTS.

SPECIFICATION forming part of Letters Patent No. 405,480, dated June 18,1889.

Application filed August 30, 1886. Serial No. 212,199. (No model.)

To all whom it may concern.-

Beitknown that we, THEOPHILUS VAUGHAN HUGHES, of l-Iolywell, NorthWVales, and CHARLEs ROLAND CHAMBERS, of South Kensington, in the countyof Middlesex, England, have invented certain new and useful Improvementsin the Manufacture of Carbon Filaments for Electric Lighting, of whichthe following is a full, clear, and exact description.

The object of our invention is to produce filaments of greater densityand homogeneity, and consequently of greater durability, than thosemanufactured by the ordinary methods.

The invention consists in the method of manufacturing carbon filamentsby the destructive distillation of a gaseous carbon com.- pound capableof yielding carbon when decomposed by heat, whereby we obtain finehair-like filaments which undergo no appreciable change in theirhomogeneity during.

the subsequent process of lamp-making, as almost all of the hydrogen hasbeen eliminated during their formation.

Reference is to be had to the accompanying drawing, forming a part ofthis specification, which represents an apparatus by which our improvedprocess of manufacturing carbon filaments may be carried outeffectively, and the figure represents a vertical section through afurnace with a retort in position.

Heretofore it has been usual to manufacture carbon filaments bycarbonizing the filamentous material bybaking it when the same is bentinto the intended shape. This process, however, destroys the homogeneityof the filaments by rendering them porous, and this defect is onlypartially remedied by the subsequent process known as flashing. By ourimproved method the said operation of baking is avoided, as thefilaments from the time of their formation are of dense hard carbon ofgreat purity and having a low specific resistance. The great density ofthe filaments produced by the method of our invention is due to theirformation (more or less molecular) directly from a gaseous carboncompound capable of yielding carbon when" decomposed by a hightemperature, the carbon being deposited and the hydrogen escaping. Thesehair-like carbon filaments combine with density great strength andflexibility, so that they may be bent and twisted into various shapesand will spring back to their original form on being released.

The process of this invention is carried on in a nearly-closed retortplaced in a furnace, the gas being conveyed into the retort at or justabove atmospheric pressure through a distributing inlet or nozzle, fromthe orifices of which the gas issues in fine streams directed againstthe sides of the retort. The gas on striking the heated sides of theretort becomes decomposed, and carbon is at first deposited upon thesides and bottom of the retort and over the nozzle in the form of aloosefibrous or cobweb-like mass. This deposit having been formed and the gascontinuing to be supplied,

the deposit now takes the form of hair-like filaments, growing, as itwere, out of the lining as a base toward the central and upper part ofthe retort,which ultimately becomes n early filled with a loose and butslightlyentangled mass of said filaments growing .more or less in thesame general direction, and of a length of four or five inches, (more orless,) according ot the size of the retort employed. The formation ofthe hair-like threads or filaments of carbon above referred to is due tothe carbonization or decomposition of streams or columns of gas invertical or gyratory motion, which are set up or formed within the hotchamber, the result being that the carbon constituent of the compound iscaused to segregate about the axis of motion of the gyratory or verticalcolumn or stream while the hydrogen passes off, the formation of thesegyratory or vertical columns being the natural result of the conditionsexisting within the retort. When the operation is completed and theretort has become cool, it may be opened, and the long filaments canthen be easily removed. The filaments are now ready for mounting andflashing.

The conditions which we have found to be essential to the properformation of the filam ents are as follows: The temperature should bethat at which the thorough decomposition of the gas used takes place,and should be maintained as constant as possible during the operation.WVe prefer to use a gas containing about forty per cent. hydrogen, andnot less than forty-five per cent. marsh-gas, together with other usualhydrocarbons equivalent to about seven per cent. ethylene. Such a gasmay be obtained from North Staffordshire coal. 'Where the gas of therequired composition is not at hand, ordinary lightinggas may be treatedby passing it over hydrocarbons to enrich it, or if too rich bydepriving it of its carbon by passing it over heated brick or charcoal.The gas must be as free from moisture as possible, the presence ofmoisture in any appreciable quantity being fatal to the formation of thefilaments. The gas should, therefore, be passed through refrigeratingworms and over quicklime. The flow of gas and time of firing vary withthe size of the apparatus; but if the flow be too rapid or the gasitself be too rich no filaments will be formed.

Having explained-the process in its general outlines, we will nowproceed to describe the means we have adopted for carrying it out inpractice; but we would have it understood that our invention is notlimited to the particular apparatus herein described, which may bemodified according to circumstances, nor to the particular compositionof gas above specified.

The retort we prefer to use is a crucible a, of plumbago or iron, of asize known as Morgans one hundred and thirty pounds. It is placed in afurnace of any suitable construction.

I) is a distributing inlet or nozzle leading ihrough the bottom of thecrucible. It is provided with a number of radial orifices 19* at theupper end, through which the gas issues into the crucible. Theseorifices may be six in number, and for a crucible of the size abovementioned should be about a quarter of an inch in diameter. The nozzleis made of fireclay and passes through a hole in the bottom of thecrucible, which is seated upon a flange 1) formed upon the nozzle. Thepipe 0, for conveying the gas to the nozzle, passes in under the furnaceand is attached to the nozzle 1), preferably by a flange d, screwed onthe pipe, bolted to a split collar 6., embracing the base of the nozzle1), a gas-tight joint being made between the flange b on the inlet 1)and the flange d on the pipe with red-lead paint and hemp. The flange bof the inlet should be about two inches below the level at which thefurnace-bars will be placed and in the center of the furnace. Thecrucible is bedded on the flange b with fire-clay suitably tempered,which is forced up around the nozzle 1;

to make a thoroughly gas-tight joint, dry powdered clay being sprinkledaround the nozzle nearly up to the level of the inlet-holes and thenwell tamped down. The mouth of the crucible is now closed by a disk offire-clay f placed within it an inch or two below the lid g, theintervening space It being filled up with wet luting-clay, with whichmay be mixed pieces of broken pot. The shrinkage of this clay plug indrying leaves a minute annular space around the mouth of the cruciblefor the escape of the hydrogen resulting from the decomposition of thehydrocarbon. The lid 9 is luted on and a heavy weight placed on it.

To prevent the crucible shifting in the furnace, it may be packed withclay wedges at the sides. The furnace-bars are now put in and the firelighted.

To permit the escape of steam from the luting-clay when drying andprevent it blowing back and condensing in the pipes, a stopcock 1' isplaced on the pipe 0 and immediately next to it a blow-off cock is, theformer being closed and the latter being opened while the crucible isbeing heated. When all the steam has been expelled, 7c is closed and iopened to allow the flow of gas to commence. cible should be kept asconstantly as possible at a bright red heat for five to seven hours,after which it is allowed to cool, the gas continuing to be admitteduntil the crucible is cool enough to permit of its removal.

The crucible must on no account be jarred or disturbed when adding freshfuel.

WVe claim The herein-described process of manufacturing dense,homogeneous, resilient, and hair-like carbon filaments for glow-lamps,which process consists in causing a gaseous carbon compound (capable ofyielding carbon when decomposed by heat) to undergo decomposition in aheated retort, the gases while undergoing the decomposition having suchmotions impressed upon them that vertical or gyrating currents of gasare set up through the atmosphere of the retort, from which currents thecarbon resulting from the decomposition segregates directly in the formof filaments, as hereinbefore described.

The foregoing specification of our improvements in the manufacture ofcarbon filaments for electric lighting signed by us this 30th day ofJuly, 1886.

vTHEOPHILUS VAUGHAN HUGHES.

CHARLES ROLAND CHAMBERS.

lVitn esses:

JNo. DEAN, ARTHUR R. SKERTEN, Both of 17 Gracechurch Street, London, E.O.

The cru-.

